A rotary electrical machine of the alternator-starter type comprising electronic power means is known from FR-2886477B1. These electronic power means include a power transistor bridge of the MOSFET type, and provide a reversible analogue-digital (AC/DC) power converter function.
In the mode in which the rotary electrical machine is functioning as an alternator, the converter provides rectification of alternating phase voltages produced by the alternator into a direct supply voltage (typically 14 Volts) which supplies an on-board supply network of the vehicle. In the mode in which the rotary electrical machine is functioning as a motor/starter, the converter provides phase voltages which supply stator windings of the rotary electrical machine. Rotation of the rotor of the rotary electrical machine with sufficient mechanical torque is thus created, so as to assure the starting of the thermal engine of the vehicle. The phase voltages which are supplied are obtained by chopping, by means of the power transistor bridge, of the on-board supply network direct voltage (direct voltage supplied by an energy storage battery).
The electronic power means according to FR-2886477B1 comprises three identical bridge branch modules and a control module which incorporates a circuit of the ASIC type. The bridge branch modules each form a branch of the transistor bridge.
The architecture of the bridge branch module according to FR-2886477B1 is represented in FIG. 4C of this patent. MOSFET transistors, in the form of bare electronic chips, are soldered onto connection gates known as leadframes, which are over-moulded in a mechatronic housing. These leadframes are kept in position on a metal bearing plate by means of an electrically insulating plate which is sandwiched between the leadframes and the bearing plate. The insulating plate has properties of good thermal conduction, so as to transmit the calories which are generated by the electronic chips to a heat dissipater placed below the metal bearing plate of the module.
The technology disclosed by FR-2886477B1 has various applications in rotary electrical machines, and in particular gives very good results in terms of quality and performance, in its application to an alternator-starter.
In the context of reduction of emissions of CO2 and the development of high-performance alternators, it is desirable to provide new technology which makes possible greater integration and reduction of costs.